Niner 2021 SIR 9 Hardtail Mountain Bike Frame (Cement/Black/Copper)

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Niner 2021 SIR 9 Hardtail Mountain Bike Frame (Cement/Black/Copper)
Price: $1,260.00
Discontinued Online
This item is discontinued and no longer available for purchase. You may want to search our site for a similar item.

There’s a new bike in town and it’s built to last, not let you down. When you’re spinning up steep climbs, bombing down the backcountry and grinding out the final miles as the sun sinks into the horizon, you need a bike you can trust. A comfortable, capable, hand-built bike made from proven, air-hardened, heat-treated steel. That’s right, steel. Because Steel Is Real and it’s fully optimized in the SIR 9.

The classic steel frame construction gives you the comfortable, durable, capable, "ride hard, put away wet" mentality that you have always wanted in a frame. No fewer than 18 threaded mounting bosses for racks, fenders, frame bags, bottles, and even a top-tube bento box. "Trail country" geometry delivers optimum performance on long pedaling rides, stiff climbs, extended descents, and spicy technical sections. With clearance for up to 29 x 2.4' tires or 27.5 x 3.0, you can go farther and stay out longer.

Build it your way with the SIR 9 frame-only option. Run it geared. Run it singlespeed. Nearly any drivetrain you can imagine is within reach, and Boost hub spacing gives you freedom for all the wheel and tire options you could want. This steel frame is ready for adventure. 


  • Reynolds 853 steel frame construction because "steel is real"
  • No fewer than 18 mounting bosses for bags, racks, bottles, and more
  • Biocentric 30 bb gives you the freedom to run whatever drivetrain you desire
  • Trail ready geometry provides a longer top tube and slacker head tube for more stability at speed
  • Integrated dropper post routing for a clean setup
  • Tire clearance for up to 29 x 2.4" or 27.5+ tires

Frame: Hand Welded Reynolds 853 Steel
Fork: N/A 
Max Front Suspension: 120mm    
Color: Cement/Black/Copper  
Available frame sizes: S, M, L, XL 
Seat collar size: 34.9mm  
Seat post size: 30.9mm  
Max Rear rotor size: 180mm  
Max Chainring Size: 1x max chain ring size 36T - Boost chainring recommended     
Front Deraileur Type: 34.9 side swing, front full    
Cable routing: External  
Headset size: 1.125" x 1.5" tapered zero stack head tube, 44mm upper, 56mm lower, (Cane Creek description: ZS442/28.6 ZS56/40)  
Chainring compatibility: standard 1x, 2x, and 3x systems  
Q-Factor: 168mm  
Bottom Bracket type: 73mm PF30 BB Shell (adaptors required for BSA Type BBS) (compatible with Biocentric 30BB 
Brake mount type: Post mount  
Rear wheel spacing: Boost 12 x 148mm 
Front wheel spacing: Boost 15 x 110mm 
Max tire size: 29 x 2.4 or 27.5 x 3.0 (varies by brand, some tires may not fit)

This product was added to our catalog on October 19, 2020

Randall Runtsch
Verified Owner
Sunday, Mar 7 2021 (about 2 years ago)
Niner 2021 SIR 9 Hardtail Mountain Bike Frame (Cement/Black/Copper) (XL)
While I have not built the bike yet, the Niner Bikes 2021 SIR hardtail mountain bike frame, in size XL, is beautiful. It seems to be well-constructed of Reynolds 853 steel. The paint job is gorgeous and shows great attention to detail.

Also, Performance Bicycle packed the bike frame well and shipped it quickly. I am very happy with the service.

Sizing Recommendations for Riders Who Fall Between Sizes:

  • Sizing down will provide a more maneuverable ride while sizing up will provide more stability
Rider Height (Feet)Rider Height (Meters)
XS5' - 5'5"1.53 - 1.65m
S5'3" - 5'9"1.6 - 1.75m
M5'8" - 6'1.73 - 1.83m
L5'11" - 6'3"1.8 - 1.91m
XL6'3" - 6'7"1.91 - 2.01m

Note: All sizing recommendations are provided by the manufacturer and may differ for each rider.


Fork Travel120mm120mm120mm120mm
(A) Top Tube Length595mm603mm627mm652mm
(B) Seat Tube Length396mm421mm485mm533mm
(C) Chainstay Length Actual430mm430mm430mm430mm
(D) Horizontal Chainstay427mm427mm427mm427mm
(E) Front Center693mm711mm737mm764mm
(F) Wheelbase1118mm1136mm1162mm1189mm
(G) Bottom Bracket Drop52mm52mm52mm52mm
(H) Headtube Length100mm110mm125mm145mm
(I) Headtube Angle68.0°68.0°68.0°68.0°
(J) Seat Tube Angle74.0°74.0°74.0°74.0°
(K) Standover Height721mm739mm791mm830mm
(L) Reach410mm425mm445mm465mm
(M) Stack611mm620mm634mm652mm
Fork Travel120mm120mm120mm120mm
(A) Top Tube Length23.4"23.7"24.7"25.7"
(B) Seat Tube Length15.6"16.6"19.1"21"
(C) Chainstay Length Actual16.9"16.9"16.9"16.9"
(D) Horizontal Chainstay16.8"16.8"16.8"16.8"
(E) Front Center27.3"28"29"30.1"
(F) Wheelbase44"44.7"45.7"46.8"
(G) Bottom Bracket Drop2"2"2"2"
(H) Headtube Length3.9"4.3"4.9"5.7"
(I) Headtube Angle68.0°68.0°68.0°68.0°
(J) Seat Tube Angle74.0°74.0°74.0°74.0°
(K) Standover Height28.4"29.1"31.1"32.7"
(L) Reach16.1"16.7"17.5"18.3"
(M) Stack24"24.4"24.9"25.7"